Automatic ignition shut-off switch



Oct. 28, 1958 D. M. LARDI AUTOMATIC IGNITION SHUT-OFF SWITCH 2 Sheets-Sheet 1 mm mm m m M w ATTORNEY Oct. 28, 1958 D. M. LARDI 2,857,899

AUTOMATIC IGNITION SHUT-OFF swmca Filed Oct. 5, 1955 2 Sheets-Sheet 2 IN V EN TOR.

DOM/N/C M. LARD/ BY /7 TTORA/f) United States Patent AUTOMATIC IGNITIQN SHUT OFF SWITCH Dominic M. Lardi, North Canaan, Conn. Application October 5, 1955, Serial No. 538,731

7 Claims. (Cl. 123-1465) This invention relates to internal combustion engines and more particularly to an automatic ignition shut-off switch for use on such engines.

One object of the present invention is to provide a protective switch for an internal combustion engine which will automatically open the electrical circuit in the ignition system, if for any reason the engine stops turning, thus protecting the wiring circuits, coils, ignition contact points and the main source of electrical supply, generally a battery, from damage or unnecessary use if for any reason the conventional ignition switch is shorted out or not turned to the off position when the engine stops turning.

Another object is to provide an automatic shut-off switch for the ignition system of an internal combustion engine, which will be controlled by the vacum created in the intake manifold of said engine or by any other source of vacuum being created by said engine, as by the use of vacuum pumps, vacuum boosters and etc.

Still another object of this invention is to provide a device which will function automatically and positively under all conditions, whether the engine is turning or not, and even when the manifold pressure is under a reduced or varying state such as when the engine of an automobile is under a load or climbing a hill.

Another object is to provide a device using pneumatic and electrical means for its operation and control of the ignition system of an internal combustion engine wherein these means are dependent for their operation upon pneumatic and electrical conditions being created by or on said engine.

A further object is to provide a pair of pneumatically operated switches, which are automatically and selectively operable from a common source of pressure or vacuum.

Yet a still further object is to provide a device equipped with a pair of electrical switches, one of which is both vacuum operated, and electro-mechanically operated, the

other switch being vacuum operated, both of said switches being connected to a. common source of vacuum, the second switch being effective to control the first switch under certain varying conditions of vacuum created by the load changes of the engine.

A further object is to provide a device of the above design, which will be simple in. construction, inexpensive to manufacture, easy to install and operate automatically under all conditions, compact, ornamental in appearance and very efficient and durable in use.

With these and other objects in view, there has been illustrated on the accompanying. drawings, one form in which the invention may conveniently be embodied in practice.

In the drawings,

Fig.v 1. represents a side viewof one form of an automat-ic ignition shut-off switch embodying. my present invention.

Figa. 2is a top plan view of the same invention.

Fig. 3 is a vertical cross-sectionahview of the same.

2,857,899 Patented Oct. 28, 1958 Fig. 4 is a schematic diagram showing the invention in one manner of use.

Referring now to the drawings in which like reference numerals denote corresponding parts throughout the several views, the numeral indicates generally one form in which the present invention may be embodied in practice.

The device includes a generally disk-shaped body 11 provided with a suitable mounting bracket 12. The upper and lower faces of the body 11 are preferably dished out and a pair of circular, flexible, airtight membranes 13 and 14 are secured about their peripheries to the upper and lower faces of the body 11 by means of a pair of circular covers 15 and 16 respectively, these covers being attached as by means of screws 17, so that an airtight seal is formed between the body 11 and the annular margins of the membranes 13 and 14.

Mounted centrally on top of the cover 15 by means of base 26 is case 18 for enclosing an electro-magnetic switch comprising a coil winding 19 surrounding an armature 20 which is slidable therewithin having a stem 21 projecting from its upper end and having a stem 21a projecting from its lower end. A disk-shaped electrically conductive member 22 forming a self adjusting moving contact is loosely received on the stem 21, being insulated from a stem 21 and the coil spring 23 by means of insulating washers 101, 102 and an insulating sleeve 103. The member 22 is held in position on the upper end of the armature 20 by means of the coil spring 23, the upper end of said spring being retained by means of a C-shaped clip 24 which snaps into an annular groove on the upper end of the stem 21. The lower end of said coil spring 23 rests on insulating washer 102', thus being retained in an insulated manner from the electrical contact 22.

The second stem 21a projecting from the lower end of the armature 20 extending downwardly through a central opening provided in the base 26 of the case 18 and a similar opening in the cover 15 is provided as a means to establish an airtight connection between the lower end of the armature 20 and two support stop washers 27, located on opposite sides of the flexible diaphragm 13. These washers are held in place by means of a screw 25, which is received in a threaded bore provided for in the stem 21a on armature 20 so as to form an airtight connection with the membrane 13 and the support stop washers 27.

A coil spring 29 is positioned between the base 26 and the lower shoulder of the armature 20 and acts to urge the armature 20 in an upward direction.

A pair of stationary electrical contacts 30 and 31 are located on opposite sides of the case 18 and are insulated therefrom. These contacts are located below the contact member 22 so as to establish a closed electrical circuit therewith when the armature 20 is moved downwardly against the force of the-coil spring 29.

A protective cover 18a is fitted to the top of case 18 to prevent dirt from interfering with the enclosedparts.

The lower cover 16 is provided with a central opening 32 to admit a stem 33 which is attached to the lower flexible membrane 14 with a pair of support stop washers" 34 located on opposite sides of the membrane 14 secured in an airtight connection with said membrane by means of a screw 35 which is received in a threaded bore 350 located in the upper portion of the stem 33.-

The spring support bracket 36 is secured to the lower cover 16 with its lower portion having a circular opening 36a provided to receive and guide the stem 33 in a sliding manner and also to support one end of a coil spring 37 which surrounds the stem 33, the other end of said coil spring being adjustably secured by a nut 38 threaded on. the lower end of the stem 33.

A switch 39 is attached to the under side of the cover 16 by means of bracket 39a (Fig. 1) this switch having a pair of contacts which may be opened or closed respectively by means of a movable, actuating finger 40, which bears against the circular shoulder 104 on the stem 33 receiving motion therefrom for actuation of the contacts in switch 39.

The body 11 is also provided at one point along its periphery with a port 41 through which is connected the conduit 42 which may lead directly to a source of vacuum, or as in the present illustration may be connected to a T 43 having conduits 44, 45.

A passage 46 which is provided in the body 11 establishes communication between the port 41 and the underside of the body 11, forming with the flexible membrane 14 a lower chamber indicated generally at 47.

A bleeder passage 48 is also provided which extends between the upper and lower surfaces of the body 11 andestablishes communication between the lower chamber 47 and the upper chamber indicated generally by the number 49 between the upper face of the body 11 and the flexible membrane 13.

The automatic ignition shutofl? switch is adapted to operate in connection with a conventional internal combustion engine indicated at 50, having a carburetor and air cleaner 51 connected to an intake manifold 52 for a source of vacuum with a generator 53 driven by belt 54 from the main crank shaft, not shown, on the engine 50. It can also be adapted to function on any other type of engine or device requiring such a switch using any other source of vacuum, such as vacuum pumps vacuum boosters, etc.

The intake manifold 52 is provided with a nipple 55 which communicates with the interior of the manifold to provide a source of vacuum, being created during operation of the engine 50 for such auxiliary devices as a windshield wiper, vacuum operated brakes etc. as is the usual practice in motor vehicles.

A flexible tubing 56, which is usually connected to the nipples 55 to supply these devices, may instead be connected to one of the conduits 45 on the T 43, the other conduit 44 being connected to the nipple 55 by suitable means such as a flexible tubing 57, whereby the vacuum created within the manifold 52 may be supplied to a windshield wiper etc. through the tubing 56, as well as to the interior of the switch 10 through the conduit 42, the port 41 and the passage 46.

A pairof wires 57a and 58 which are connected respectively to the contacts 30, 31 on the switch, and are located in the usual circuit (not shown) which includes the vehicle battery, the conventional ignition switch, and the primary of the ignition coil, the connection being made in'such away that a disk contact member 22 of the switch 10 will open or close respectively the circuit between the battery and the ignition coil in series with the conventional ignition switch.

One end of the coil winding 19 is connected to a post 59 which is attached to and insulated from case 18, while the other end of the winding of the coil 19 is connected to some metallic portion of the switch 10 so as to be connected with the common ground of the vehicle and engine when the bracket 12 is attached to some metallic portion of said vehicle or engine.

The binding post 59 is also connected by a wire 60 to a connection 61 on the switch 39, the other connection 62 of this switch being attached by a wire 63 to the hot side of the generator 53 as indicated by an insulated binding post 64 on the generator. The other connection 65 of the generator 53 is normally connected tothe common ground.

Operation .With: the automatic ignition shutofi switch 10 connected as shown in Fig. 4, the operation of the device will be as follows:

When it is desired to start the engine 50, the conventional ignition switch (not shown) on the vehicle will be closed, thus establishing a closed circuit between the ungrounded side of the vehicle battery and one of the wires 570 or 58, the other of said wires being connected to the ungrounded side of the ignition coil.

The grounded side of the battery and the ignition coil will complete the circuit, except for the fact that the connection between contacts 30 and 31 of the switch 10 will not be established so long as the spring 29 maintains the armature 20 in its uppermost position, as shown in Fig. 3.

However, as soon as the crankshaft of the engine 50 begins to revolve in response to the operation of the usual starting motor (not shown), a vacuum will be created within the intake manifold 52, in response to movement of the pistons within the cylinders of engine 50.

The influence of this vacuum introduced into the chamber 47 of the switch 10 through the passage 46, and to the chamber 49 through the bleed passage 48, will cause the upper membrane 13 acting under the force of differential pressure created by the atmosphere outside of the chamber 49 to pull the armature 20 downwardly against the resistance of the spring 29, until the contact member 22 completes the circuit between the contacts 30 and 31. In order to establish a good electrical connection between these members, the coil spring 23 will permit a certain amount of downward overtravel of the armature 23 after the contact 22 has first engaged the contacts 30, 31.

In addition the influence of vacuum in the chamber 47, during conditions which usually prevail when the engine 50 is being started, will cause the lower membrane 14 to be forced upwardly under the influence of differential pressure created by the atmosphere so as to raise the stem 33 against the downward force exerted by the coil spring 37. This action will permit the actuating finger 40 to move upwardly to open the contacts in switch 39, and break the connection through the wires 60 and 63 between the winding 19 and the generator 53.

In this connection it should be noted that'while a circuit is normally established betweenthe engine battery and the connection 64 of the generator when the engine 50 is operating for the purpose of continually recharging the battery, usually, a relay means (not shown) is provided, whereby the connection between the generator when the engine 50 is idling or running at low speed..

Thus unless the engine 50 is operating above a predetermined low speed, no current will flow between the battery and coil through the switch 39.

In any event, so long as the contact member 22 establishes a circuit between the contacts 30 and 31, and so long as the usual ignition switch is in the on position, current will be supplied from the battery to the ignition coil, and the engine 50 will be in condition to continue operation.

Under normal conditions of operation when the engine 50 is called upon for only moderate amounts of power, such as when a vehicle is being driven at cruising speeds along substantially level highways, the vacuum existing in the intake manifold 52 will be sufficient to maintain both the membranes 13 and 14 in their collapsed position, with the ignition circuit established between contacts 30, 31 and the member 22, and with the switch 39 in its open position whereby no current is flow ing to the coil 19 from generator 53.

However when the engine 50 is asked for a sudden surge of extra power, or when it is being operated at maximum capacity, the resultant opening of the butterfly valve in the carburetor 51, will cause a marked reduction in vacuum created in the manifold 52, whereby depending upon the strength of the spring 29, the atmospheric pressure acting on the membrane 13 will' no longer hold the armature 20 and the contact member 22 in position to connect contacts 30 and 31, in which case regardless of the position of the conventional ignition switch, the circuit between the engine battery and the ignition coil of the engine would be broken and the engine 50 would cease functioning.

This undesirable condition is averted by my new invention because of the fact that any reduction in the vacuum in the chamber 49 would be reflected first and in a more marked degree in the chamber 47, so that the stem 33 will move downwardly whenever the atmospheric pressure acting on membrane 14 is insuflicient to overcome the force of the coil spring 37, until the circular shoulder 104 moves the actuating finger 40 downwardly to close the contacts in the switch 39, allowing current to flow from the generator 53 to the coil winding 19 and this energizing of the coil will be sutficient to hold the armature 20 in its downward position to maintain the member 22 in contact with the contacts 30, 31, so long as current is being generated by the generator 53.

Thus it will be seen that so long as the engine 50 is operating, and the ignition switch is turned to its on position a closed circuit will be maintained between the battery and the ignition coil, either as a result of vacuum developed within the manifold 52 or, if such vacuum is insufficient, then by energization of the coil 19.

As a precaution against the temporary interruption of the ignition circuit, as when a reduction in the vacuum being created in the manifold 52 is about to cause the coil spring 29 to break the circuit between the contacts 22, 30 and 31, a means is provided in my invention whereby closing of the switch 39 will cause energization of the winding 19, thus holding the armature 20 and the contacts 22, 30, and 31 down before any further reduction of vacuum causes the release of the armature 20.

This is accomplished by adjusting the tension of the spring 37 by rotation of the nut 38 on the stem 33, until the force exerted by this spring will be sufficiently greater than the force exerted by the spring 29 so that at the instant that a reduction of the vacuum pressure is reflected by the two flexible members 13 and 14, the spring 37 acting against the membrane 14 through the stem 33 will cause this membrane to start retracting back away from the disk 11 before the flexible membrane 13 will start to retract. Thus it will readily be seen that, as the flexible membrane 14 and the circular shoulder 104 located on the stem 33 begin to retract due to a decrease in vacuum being created by the engine, and because the spring 37 is adjusted to exert more force than the spring 29, the shoulder 104 will act against the part 40 which in turn will move the electrical contacts in the switch 39 to a closed position before the spring 29 can cause electrical contact to be broken to the ignition coil by the armature 20 being forced upward. The closing of the electrical contacts in the switch 39 will instantaneously cause an electrical current to flow from the generator 53 through the Wire 63 to the coil windings 19 surrounding the armature 20 and create an electro-magnetic force sufiicient to assure that the armature 20 will not retract and cause electrical contact to be broken at the contacts 30 and 31. Also it is important to understand that an important feature of my invention is the fact there is a certain difference in diameters between the port 46 and the bleed port 48. Tests have shown that it is more advantageous to have the bleed port 48 smaller in diameter than the port 46. This can be understood when we consider the following. It will be noted that whenever there is a decrease in vacuum coming through the port 46 to the chamber 47 there will be a slight lag before the vacuum pressure in the chamber 49 will decrease to equal the vacuum pressure in the chamber 47 because of the resistance presented by the smaller size of the port 48.

This lag will tend to assist in retaining the member 13,

the armature 2 0 and the contacts 30, 31 and 22 in a downward position to maintain electrical contact to the ignition coil, until the contacts in the switch 39 have closed the circuit to the coil 19. Also it will be found that as the membrane 14 starts to retract because of a decrease in vacuum, it will tend to maintain or increase the vacuum in the chamber 49 by the suction created by the retracting membrane 14 in the chamber 47 through the bleed port 48. Although this explanation must of necessity be lengthy, it is to be understood that the foregoing operations would occur almost instantly and automatically in actual operation.

Furthermore, the size of the bleed port 48 can be such as to positively insure that air will be withdrawn from the chamber 47 under the influence of vacuum in the manifold 52 at a greater rate than it is withdrawn from the chamber 49, whereby when the engine 50 is being initially turned over by a starting motor, the circuit for the energizing coil 19 will be positively disconnected prior to the completion of the circuit to the ignition coil of the engine 50.

It will thus be seen that the automatic ignition shutoff switch embodying the present invention will be effective to disconnect the engine battery from the ignition coil of the engine whenever the engine is at rest irrespective of the causes for stoppage of the engine and regardless of whether or not the usual ignition key has been turned off or is on.

One of the advantages of this invention is the fact that there will be no danger of ignition coil burn out or a run down battery, as is often the result when, for example, the engine has been left running at idling speed, unattended by the operator and has stalled while the conventional ignition switch is in the on position.

Another advantage is the fact that if a vehicle operator happens to turn the ignition switch on but does not immediately start the engine, or if the engine is stopped for any reason and the operator should forget to turn the ignition key off, there will be no danger that the vehicle battery will become discharged.

While there has been disclosed in this specification, one form in which the invention may be embodied, it is to be understood that this form is shown for the purpose of illustration only and that the invention is not limited to the specific disclosure but may be modified and embodied in various other equivalent forms without departing from its spirit. In short, the invention includes all the modifications and embodiments coming within the scope of the following claims.

Having thus fully described my invention what is claimed as new and for which it is desired to secure Letters Patent is:

1. In an automatic ignition shut-off system for an internal combustion engine, including a generator driven by said engine, a battery-energized electric circuit including a switch urged by a spring to open position, an ignition coil, an electro-magnetic coil energized by the current in the generator circuit to oppose said spring, means responsive to a normal vacuum in the intake: manifold of said engine to mechanically maintain said switch in closed position, means responsive to a low vacuum condition in said manifold to cause said generator to energize said electro-magnetic coil to keep said switch closed and prevent said engine from stopping, said spring being operative by the accidental stopping of said motor to open said I switch and prevent the battery from running down.

2. In an automatic ignition shut-off switch for an internal combustion engine having a rotatable drive shaft and a generator, a battery-energized electric circuit including a switch biased to open condition, an electro-magnetic coil in circuit with said generator for closing said switch, means responsive to a vacuum in the intake manifold of said engine to energize said coil and maintain said switch in closed condition, current generator means responsive to the rotation of said shaft, a low vacuum operated switch for the generator biased to closed condition, said biases being ineffective under normal conditions of vacuuminsaid intakemanifold, said two biases being efiec tive only under conditions of reduced vacuum to energize said coil and maintain the circuit in the closed condition, said first mentioned switch being opened wherever said engine stops to prevent the engine battery from running down.

3. In automatic switches for the ignition circuit of an internal combustion engine having an intake manifold and a source of electrical energy effective during operation of the engine, the combination comprising a pair of closed chambers, each of said chambers having an element movable in response to differential of pressures between the inside and outside of said chambers, means to place the interior of one of said chambers in communication with the intake manifold of an internal combustion engine, means to place the interior of said second closed chamber in communication with theinterior of the first chamber, a pair of. contacts for said ignition circuit, one of said contacts being movable to open and close the ignition circuit, an electro-magnetic switch means actuatable to move said movable contact to close said circuit, means to connect said movable contact with the movable element of said second chamber, whereby said movable contact may be actuated either by response to changes in differential pressure in said second chamber or by said electromagnetic means, switch means connected with said electro-magnetic switch means and said source of electrical energy to actuate said electro-magnetic switch means and differential biasing means for said movable elements of said closed chambers, whereby the pressure differentials in said chamber under normal operation of said engine will be effective to prevent actuation of said electro-magnetic means and to maintain said ignition circuit closed, but under conditions of low vacuum in said intake manifold said electro-magnetic means will be actuated.

4. The invention as defined in claim 3, wherein said closed chambers comprise a disk shaped body having a pair of flexible membranes peripherally attached to opposite faces of said body, said body being provided with passage means for communication with the interior of one of said chambers :andan orifice for communication of the interior of bothrchambersa 5, The invention asudefinedin claim 3, wherein said electro-magnetic means, comprises an armature connected to said movable contact and a coil to be energized to move said armature, said armature being alsoconnected to said movable element of said second chamber, said biasing means comprising a spring means to urge said movable contact to open said ignition, circuit and spring means to urge said switch means to closethe circuit to energize said coil, said second spring means being adjustable to providegreater resistance to pressure differential than said first spring means. l

.In a pneumatically, operated switch, the combination comprising first and second electrical contact means, first and second pneumatic means connected to said first and second contact means respectively, to actuate said contact means in response to predetermined differentials of pressure, electromagnetic means connected toactuate said first contact means irrespective of said pneumatic means, said second contact means being arranged to be connected to a source of current to control said electromagnetic means, said second pneumatic means comprising a closed chamber provided with an orifice for connection to a source of differential pressure, said first pneumatic means having a closed chamber, passage means cornmunicating between said first and second closed chambers other than through said orifice in said second chamber, said passage means being constricted, so that when a change in pressure differential occurs at said orifice, said second pneumatic means will be affected prior to said first pneumatic means.

7. The invention as defined in claim 6, wherein said first and second chambers are provided with a common partition, the diameter of said passage being less than the diameter of said orifice.

References Cited in the file of this patent UNITED STATES PATENTS 1,952,667 Geraghty Mar. 27, 1934 2,158,428 Robertson May 16, 1939 2,311,179 Berry Feb. 16, 1943 

